1. Field of the Invention
The present invention relates to a solid oxide fuel cell.
2. Description of the Related Art
JP 2009-134930A discloses a segmented-in-series fuel cell. This fuel cell has an insulating substrate and a plurality of cells provided on the insulating substrate. The fuel cell has an anode (fuel electrode), an electrolyte layer made from yttria-stabilized zirconia (YSZ: (Y2O3)X(ZrO2)1-X (wherein x is 0.05 to 0.15)), and a cathode (air electrode) that are stacked in sequence. Adjacent cells are electrically connected to each other in series via a current collector and an interconnector made from lanthanum chromite. Moreover, the fuel cell has an interlayer that is provided between the interconnector and the electrolyte layer. Specifically, in Patent Document 1, an interlayer made from Y2O3 to which 1 wt % to 20 wt % of NiO is added and that is provided on lanthanum chromite (La0.8Sr0.2CrO3) is described. JP 2009-134930A states that the interlayer can reduce a gas leak.
However, the present inventors have found that there are still some problems as follows with the conventional technique.
When the interlayer formed of NiO—Y2O3 is in contact with the lanthanum chromite interconnector, an agglomerated layer of Ni—O is formed at the interface between the interlayer and the interconnector. Ni—O is reduced to Ni at reduced atmosphere around 800 Celsius degree, and thus the volume of the Ni—O agglomerated layer is decreased. As a result, a crack in the agglomerated layer, delamination of the interlayer from the interconnector, and defects are likely to occur. Such defects result in a gas leak.